BHG. But why?

[jdub]

OK I’m not totally insane, I went and checked ARPs website for torque specs and their general torque spec for the 190,000/200,000psi tensile strength 12mm stud is 86 ft/lbs w/moly, 109ft/lbs w/30 wt. That is general torque spec maybe supra specific is a little different, or maybe they changed the specs for 2005.

Nah Man...you're not insane...you're really one of the more knowledgeable guys here. And I suffer from CRS (Can't Remember Shit) too...LOL

The torques you posted were really close...as were a couple of the other guys. +/- 5-6 lbs torque will not cause a BHG. Having said that, it makes a huge difference on what lube you use and the type of HG (metal vs. stock). I posted the spec sheet (it's a 2005 sheet BTW) just to get everyone on the same page.

Personally...I think Jon's problem is falling in the "shit happens" category. Could have got a defective MHG, head bolt could have loosened up on him, detonation...the list could go on and there not be a thing he could have done about it.

Cometic's specs recommend (from Cometic's website): "Additional sealer is not required with Cometic MLS Head Gaskets. The outer layers of the gasket are coated with a .001" thick coating of viton (a high temperature flouroelastomer)." If you're re-using a Cometic...it's probably fine to use a sealer to replace the factory coating, but that's not the case in Jon's problem. The Cometic is also more forgiving of surface RA with a value of 50RA as the requirement.

Jon said he was using bolts in the 1st post...To be honest, I don't remember what the ARP torque spec is for the bolts, but 75 ft/lbs does ring a bell. I do know the main argument for using studs is the ability to get higher torque values when using a MHG and their resistance to stretch/loosening so a re-torque is not necessary.

Also, he could have just got a bad tank of gas (i.e. the truck put 87 in the premium under ground tank)...detonation under the right conditions can really mess a HG up...metal or not.

Again...it looks like to me that Jon did everything right or at least very close. And it goes to show ya that this motor can turn around and bite ya anyway!

 

[Nick M]

Your teardown will reveal more. Think of it as a learning curve when you take it apart.

Personally...I think Jon's problem is falling in the "shit happens" category. Could have got a defective MHG, head bolt could have loosened up on him, detonation...the list could go on and there not be a thing he could have done about it.

I would really like to know what you see when you take everything apart.

See the pattern here? Take it apart and post the what you find. Then we all learn.

 

[bigaaron]

The Cometic is also more forgiving of surface RA with a value of 50RA as the requirement.

I would trust it (with 50ra) as far as I could throw it.

 

[jdub]

I would trust it (with 50ra) as far as I could throw it.

That was the minimum RA requirement...the point being that the Cometic spec is a bit more forgiving than what you see with HKS, Greddy, etc. You can polish it to a surface RA of 0 and still be in spec...course your gonna pay for that too

Here's Cometic's catalog...it's on page 3.

http://www.cometic.com/catalogs/AutoCat04.pdf

 

[IJ.]

JDub: Probably the most important part of the Cometic PDF relating to the 7M>>

Re-torque is not necessary unless using hardware that has not
been heat cycled.​

 

[jdub]

JDub: Probably the most important part of the Cometic PDF relating to the 7M>>

Re-torque is not necessary unless using hardware that has not
been heat cycled.​

Hmmm...so re-torque is a good idea even with the studs huh?

 

[IJ.]

Yep being a bit old school I always retorque anyway and I don't believe that an MLS gasket is a good candidate for a MonoTorque gasket at the best of times

 

[jdub]

Yep being a bit old school I always retorque anyway and I don't believe that an MLS gasket is a good candidate for a MonoTorque gasket at the best of times

Sigh...the devil is always in the details. I swear you have to have a Masters Degree on this car to work on it

So you have to just crack the stud nuts loose with a breaker bar to do the re-torque...correct? Following the TRSM bolt pattern as well.

No big deal I guess...I need to do a valve shim adjustment job anyway. I was planning to replace the plugs with coppers too...doing this won't be that bad while I'm there.

 

[malloynx]

same thing happened to me. installed new studs, didn't retorque and the HG leaked under heavy boost.

 

[IJ.]

JDub: Correct just back crack em then pull back to torque.

I don't think it would make any difference what order they're done in as you're not relaxing the head but I always follow the factory sequence so I don't miss any!

 

[MDCmotorsports]

Ok a little update on this.

I undid the head today to find out that this problem has been happening for a while.

1,2 & #6 exhaust valves all show signs of burning coolant.

Funny though as its never showed on the plugs.

The only failure that I see on the HG is the land that seperates #5&#6 cyls is broken on the top layer.

Also, the engine builder that I used is an ex indy car engine builder. Big difference than him and a nascar boy. Any who, I know for a fact that the head and block were GROUND not machined.

I also called the builder, and he pulled the spec sheet. Torque was 105#'s with molly lube.

Now, what headgasket to replace this one with?

 

[mkIIIman089]

I also called the builder, and he pulled the spec sheet. Torque was 105#'s with molly lube.

Man... IDK if I would trust the builder again.

 

[MDCmotorsports]

I really don't see this as the builder's fault. Really I couldnt' ask for more. The engine is almost 4 years old now with 30k miles on it and has been making nice HP for a while now.

 

[IJ.]

I still think it may have just detonated Jon!

No HG will take that.

 

[mkIIIman089]

It just seems like due to him over torquing the studs it was bound to die after 4 years. (which really isn't very long at all if you ask me)

That as well IJ could have done it.

 

[GrimJack]

One thing I didn't see mentioned here - cometic HG, but did you drill out the evil rivets?

I'm kindof assuming you did, as I expect the thing would have leaked long ago if you had not...

 

[MDCmotorsports]

Grim, surely the engine builder did. I know when I took the assembly apart today the headgasket came out in 3pcs.

 

[jdub]

One thing I didn't see mentioned here - cometic HG, but did you drill out the evil rivets?

I'm kindof assuming you did, as I expect the thing would have leaked long ago if you had not...

I thought it was the Titian that had the evil rivet

 

[siman]

There is no knowledge base difference between Nascar and Indy car engine builders. Engines are engines and those guys have had YEARS of experiance througout race car teams.

Newsflash: Just to let you guys know I work one on one with Gerre Payvis at Race Power (go ahead and search his name), ex can am driver and F5000 driver. Just me and him in the shop and nobody else. He has worked and built Nascar, Formula cars, Trans-Am cars and Can-Am cars (rebodied F5000/F1 cars). In the past 5 months I have really increased my hands on knowledge base in race cars. I work on 3 $250,000 Trans-Am cars daily. Building an ex Paul Gentalozzi (sp?) Jag for a guy in Canada. Basically making it into a mustang chassis/roll cage design and mouting a newer Ford block in it. Also nearly completed a 69' tube frame Mustang vintage racer chassis. Built a couple of small block 700hp dry sumped motors in the process too!

Anywho, Nascar is filled with guys coming from Trans-Am and Sports Car racing. Since alot of teams have split due to budget cuts Nascar has been flooded with engineers and mechanics from all racing genre's!!! Hence the reason Nascar is the #1 watched racing series in the USA. Its just COMPETITIVE.

Honestly I hate nascar for the type of "people" it brings. But I must admit it is the CLOSEST racing I have ever seen as far as the winners go. Look at the race at Talladega yesterday. Jeff Gordan was in 1st place on the last lap then ended up 15th!!!!

Look at it this way, its a hunk of metal slabbed together with bolts. Anything or anybody could make a mistake. Now we have figured out the head was torqued correctly I would say like IJ did that DETONATION is the only way that a head gasket and valves could show those particular signs or wear with a proffesionally built motor. When your running a motor to percents of its limits, it will fail. It does NOT matter how well built the motor is. The more HP your running the less its lifespan will be.

-Jonathan Mann

 

[MDCmotorsports]

Jonathan, no one is questioning you or your credentials here.